Printed circuit mounting means for switch blades



April 9, 1963 w. w. WRIGHT PRINTED CIRCUIT MOUNTING MEANS FOR SWITCHBLADES Filed May 19. 1960 /N l/E N TOR ATTORNEYS.

United States Patent Ofiiice 3,085,139 Patented Apr. 9, 1963 3,l85,139PRINTED -ClRCUiT MQUNTENG IWEANS FGR SWHTCH BLADES William WarrenWright, Wheaten, llL, assignor to Quarriian Electric ManufacturingCompany, a corporation of Illinois Filed May 19, 1960, Ser. No. 3d,l$9 1Claim. (Cl. 209 166) This application relates generally to printedcircuit constructions and more particularly to a new and improved methodand means for mounting electromechanical elements, such as switchblades, and terminal members, on printed circuit boards.

In the manufacture of printed circuit apparatus, it often is desirableto connect electro-mechanical elements to the printed circuitry, but inmany cases this practice presents serious problems. For example, thereare many applica tions where it would be advantageous to mount andattach leaf-type switch blades to a printed circuit board so that solderdip electrical connections can be made between the switch blades and theprinted circuit on the board. Various techniques have been adopted inthe past to effect such an attachment, including the use of eyelets,rivets, studs, spring clip attachments and the like, but these prior arttechniques have not proved entirely satisfactory for this purpose.

Those skilled in the art will readily appreciate that the problemspresented in the use of such prior art techniques have resulted from themany difficulties inherent in the construction and use of printedcircuit board switch blades. Thus the mounting and/or attachment of theswitch blades to the printed circuit board must be made in such a mannerthat the final assembly is capable of withstanding numerous switchingoperations without fatigue or breaking of the switch blades, withoutfatigue or breaking of the soldered connections of the switch blades tothe printed circuit, and without destroying the. bond between theprinted circuit and the printed circuit board.

Accordingly, it is a general object of this invention to provide new andimproved means and technique for attaching or mountingelectro-mechanical elements to a printed circuit board.

It is a more specific object ofthis invention to provide a new andimproved printed circuit board and switch blade assembly.

In accordance with oneof its specific features, the invention comprisesmechanical locking means for maintaining the switch blades rigidlymounted on the printed circuit board even before the switch blades aresoldered to the printed circuitry. Thus .it is a feature that thepreliminary attachment of a switch blade to the board before solderingpresents resistance to motion. transfer through the blade to theconnection area of the printed circuit.

To this end, each switch blade is formed with a recessed portion shapedto receive a locking tab adapted to be positioned between a pair ofsimilarly shaped blades. Thus each pair of switch blades are insertedthrough a suitable aperture in the printed circuit board and. therecessed portion in each blade serves to properly locate the blades withrespect to each other-so that their contact points will be aligned andwith respect to the board so that the portions to be soldered to theprinted circuit extend a-desired distance from the board.

A shaped locked tab then is inserted into the tab receiving recesses ofeach. blade and the dimensions of the tab are related to the dimensionsof the opening in the board to rigidly secure and mechanically lock theblades to the board. As the blades now are positively locked in properposition on the board, solder dipping of the final assembly for longterm positive connection is greatly facilitated.

Accordingly it is a further object of this invention to provide a novelmethod and means for positive locking of the mounted parts of switchblades in a printed circuit.

It is a still further object of this invention to provide a relativelysimple, fast and low cost assembly procedure for positioning switchblades in proper relation to each other on a printed circuit board, andin proper relation to actuating devices and to the printedcircuit.

It is another object of this invention to provide a novel method andmeans for mounting switch blades on a printed circuit board whichfacilitates solder dipping of the final assembly and which compensatesfor variations in the thickness of the printed circuit and locking tab.

In accordance with another specific feature of the invention, aneffective mechanical and electrical connection is provided between theswitch blades and the printed circuit even before the soldering thereof.To this end, each switch blade is provided with an upstanding retainingfinger that is placed in contacting relationship with the printedcircuit when the switch blade is mounted and aligned on the printedcircuit board. Such electrical connection is facilitated by the pressureor tension provided by the interaction of locking tab and the bladerecessed portions which causes the finger to be pressed firmly againstthe printed circuit. Thus, the electrical connection between the bladeand printedcircuit is made mechanically secure before soldering inaccordance with the requirements of established standards for electricalterminal apparatus.

Thus, it is still another object of this invention to provide aneffective mechanical and electrical connection of an element to aprinted circuit before soldering.

Those skilled in the art will appreciate from the present applicationthat the invention is applicable to electromechanical elements otherthan switch blades, the latter having been disclosed in detail as onlyone illustrative embodirnent of the invention. Thus, it is contemplatedthat tab or taper type terminals may be attached to a printed circuitboard support by utilizing the principles of the invention. Suchattachment provides an inherent mechanical stability so that theinsertion and removal of a mating electrical connector places little orno strain on the soldered electrical connection.

Further, the methods and means of attachment to the printed circuitboard comprising the present invention facilitates the removal orreplacement of the switch blades or terminals in a comparatively simplemanner. This may be effected merely by removing the locking tab, heatingthe solder and pressing the blade or terminal inward toward the aperturein the printed circuit board. Thus, simple field repair of a circuit ispermitted without the need for complicated tools.

It is still another object of this invention to provide such a novelmethod and means, as above, which enables a greatly improved mechanicaland electrical connection of an electro-mechanical element, such as aswitch blade or terminal member to a printed circuit.

The above andother novel objects and features which are characteristicof the invention are set forth with particularity in the appendedclaims. The invention itself, however, both as to its organization andmethod of, operation, together with further objects and advantagesthereof will best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings inwhich:

FIGURE 1 is a perspective view of an illustrative printed. circuit boardand switch blade assembly embodying the invention;

FIGURE 2 is a front elevational view and FIGURE 3 is a rear elevationalview, partly in cross sect-ion, of a portion of the invention embodimentillustrated in FIG- URE l;

FIGURES 4 and 5 are side elevational views, partly in cross section, ofan illustrative switch blade and printed circuit board assembly inaccordance with the invention, before and after solder dipping,respectively; and

FIGURE 6 is an exploded view of one embodiment of the invention,illustrating the manner in which the component parts are assembled.

Referring now to the drawing, and more particularly to FIGURE 1 thereof,there is illustrated a preferred em bodiment of the invention wherein aplurality of switch blades are arranged in operative pairs and aresecurely mounted upon a printed circuit board 10. In accordance with afeature of this invention, each pair of switch blades as, for examplethe pair of switch blades 12 and 14, is adapted to be electricallyconnected to a printed circuit 20 provided on at least one surface ofthe printed circuit board and is further adapted to be mechanicallylocked to the printed circuit board 10 as by means of a unique lockingtab 16 which cooperates with shaped tab receiving recesses formed in theswitch blades, as explained in greater detail hereinbelow.

The printed circuit board It) may take any one of a number of forms wellknown in the art for such apparatus, and in the illustrative exampledepicted in the drawing, the printed circuit board 10 takes the form ofa generally fiat member having a pair of planar surfaces 21 and 24 atopposing sides thereof.

A printed circuit, such as the printed circuit 20 shown particularly inFIGURE 3, is provided on at least one of the planar surfaces of theprinted circuit board. As well understood by those skilled in the art,the printed circuit 20 may take on any desired configuration and may bebonded to a planar surface 21 of the printed circuit board 10 in. anysuitable manner.

The printed circuit board 10 is formed with a plurality of apertures 25extending therethrough, said apertures being adapted to receive theterminals of a plurality of switch blades which are mounted upon theprinted circuit board 10 for electrical connection to the printedcircuit 20.

In addition, the printed circuit board may be formed with a furtherplurality of apertures 22 for receiving the terminals of electricalcomponents such as resistors, condensers, and the like.

Prior known techniques for mounting the switch blades to the printedcircuit board have not proved entirely satisfactory. Previously, themethods of attaching or mounting switch blades to the printed circuitboard made use of various fastening devices, such as eyelets, rivets,studs, spring-clip attachments, and the like, but those skilled in theart are familiar with the problems created in the use of such fasteningdevices.

In accordance with a feature of this invention, these prior artdifficulties are obviated by the combination of uniquely shaped switchblades and mechanical locking tabs associated therewith. As clearly seenin FIGURES l, 4, 5, and 6 of the drawing, each switch blade is formedwith a generally 'U-shaped tab receiving recess which provides severalhighly advantageous features in the assembly of the switch blades uponthe printed circuit board. Thus, the switch blade 12 is formed with theU-shaped tab receiving recess 30 and the switch blade 14 is formed withthe U-shaped tab receiving recess 32. These operatively associatedswitch blades are positioned on the printed circuit board 10 byinserting one end terminal of each switch blade through the opening 25in the printed circuit board. Advantageously, the switch blades 12 and14 are inserted through the opening 25 such that their respective tabreceiving recesses extend in opposite directions so as to enable thelocking tab 16 to be inserted therebetween.

As particularly shown in FIGURES 4 and 5 of the drawing, the tabreceiving recesses 30 and 32 serve to properly align and position theirrespective switch blades when the switch blades are inserted in anaperture 25 of the printed circuit board It Thus, a portion of each tabreceiving recess abuts one planar surface of the printed circuit boardto properly position the switch blades with respect to each other, withrespect to their associated actuating devices, and with respect to theprinted circuit.

Advantageously, this positioning of the switch blades on the printedcircuit board is facilitated by the provision of a retaining finger oneach switch blade. This is exemplified by the retaining finger 34 at oneend terminal of switch blade 12 and the retaining finger 36 at one endterminal of the switch blade 14-. Advantageously, each retaining fingermay be formed from the body of its switch blade as by making a U-shapedcut in the end terminal portion of the switch blade, adjacent the tabreceiving recess, and by extending the retaining finger thus formedoutwardly from the switch blade in the direction of the tab receivingrecess.

It can now be seen, as particularly illustrated in FIG- URE 4 of thedrawing, that the tab receiving recess and the retaining finger of eachswitch blade serves to properly position each switch blade on theprinted circuit board 10.

Those skilled in the art will readily appreciate that the preliminaryattachment of the switch blade to the printed circuit board beforesoldering must present adequate resistance to motion transfer throughthe switch blade to the connection area of the blade to the printedcircuit. In accordance with a feature of this invention, the switchblades are rigidly and securely mounted to the board in their unsolderedstate by means of a locking tab 16 adapted to be inserted between thetab receiving recesses .of an associated pair of switch blades. Thelocking tab 16, which may be tapered or rounded at one end thereof, asexemplified by the rounded edge dil in FIGURE 6, is adapted to beforce-fitted between the tab receiving recesses 30 and 32 provided inthe switch blades 12 and 14, respectively.

Advantageously, the thickness of the locking tab 16, is selected so thatthe tab fits snugly within the tab receiving recesses 30 and 32. Asclearly illustrated in FIGURE 4 of the drawings, the locking tab 16serves to position the tab receiving recesses 3t) and 32 in abuttingrelationship with the planar surface 24 of the printed circuit board 10,so as to positively lock the switch blades in proper position on theprinted circuit board.

'It can be seen from FIGURES 4 and 5 of the drawing that the lockingaction of the tab 16 properly positions the blade contacts 26 and 28with respect to each other so that a desired electrical circuit iscompleted when the switch blades are operated by their associatedactuating device. In addition, the locking action of the tab 16 servesto place the retaining fingers 34 and 36 of the switch blades 12 and 14,respectively, in adjacent relationship to the printed circuit 20, tofacilitate the electrical connection between the switch blades and theprinted circuit.

Thus, it can be seen that after the switch blades are properly assembledand mounted on the printed circuit board 10, the entire assembly may besolder-dipped to provide the desired electrical connections between theprinted circuit 20 and the switch blades. This is particularlyillustrated in FIGURE 5 of the drawing, wherein the solder portion 38can be seen as making an electrical connection between the end terminalof each switch blade and the printed circuit 20.

It will now be appreciated by those skilled in the art that theinvention provides mechanical and electrical connection of a switchblade to a printed circuit board wherein a final assembly is able towithstand many operations without fatigue or breaking of the switchblades, without breaking of the soldered connections between the switchblades and the printed circuits, and without destroying the bond betweenthe printed circuit and the printed circuit board. These advantages arederived from the fact that substantially all motion of the switch bladesoccurs at switch blade positions remote from the electrical connectionsof the printed circuit to the switch blade contacts. The locking tab 16prevents any motion transfer of the switch blades to the surface 21 ofthe printed circuit board where the electrical connection between theswitch blade and the printed circuit is made. Manifestly, this uniqueassembly serves to prevent any cracking or breaking of the solderedconnection between the blade and the printed circuit.

In addition, it has been shown that a standard rosin flux advantageouslymay be utilized in soldering the switch blade or terminal to the printedcircuit. With this arrangement, the rosin in the flux serves to glue thelocking tab firmly in place so that the end assembly is extremelystable. The subsequent unlocking of the tabs for removal necessitatesthe removal or breaking of the bond created by the rosin flux.

In addition to the above-stated advantages, the invention permits asimple, fast and low cost assembly procedure. Also, the inventionpermits a similarly simple, fast and low cost disassembly procedure whenit is desired to remove or replace the switch blades or terminals. Asstated heretofore, this operation is effected merely by removing thelocking tab, heating the solder and pressing the blade or terminaltoward the board aperture for removal therefrom.

Further, the invention provides a reduction in the overall cost of theassembly as used in production. Those skilled in the art will readilyappreciate that the switch blades or terminals can be formed with tabreceiving recesses at low cost, and that the locking tabs can be formedat low cost. Further, the tab itself compensates for normalmanufacturing tolerances. Thus, compensation is provided for variationsin thickness of the printed circuit, the printed circuit board, or thelocking tab, while at the same time, positive locking of the switchblades or terminals to the printed circuit board also is provided.

While there has been shown and described a specific illustrativeembodiment of the invention, it will, of course,

be understood that various modifications and alternative constructionsmay be made without departing from the true spirit and scope of theinvention. Therefore, it is intended to cover by the appended claim allsuch modifications and alternative constructions as fall within theirtrue spirit and scope.

What is claimed as the invention is:

The improvement of printed circuit apparatus comprising the combinationof a printed circuit board having a pair of planar surfaces and aprinted circuit bonded to at least one of said surfaces, a pair ofelongated resilient blades operatively mounted on said printed circuitboard, said printed circuit board being formed with an aperture shapedto receive said pair of blades, each of said blades having a tabreceiving recess portion and a retaining finger portion spaced from eachother a distance approximately equal to the thickness of said printedcircuit board, said portions being positioned in abutting relation toopposite planar surfaces of said printed circuit board to align saidblade on said board whereby a terminal of each blade extends throughsaid aperture and adjacent said printed circuit for electricalconnection thereto, the retaining finger portion on each blade servingto facilitate soldering of the blade to the printed circuit to eifect anelectrical connection therebetween and further to facilitate the securefastening of the blade to the printed circuit board, and locking tabmeans adapted to be inserted between said pair of blades in the tabreceiving recess portion of each blade for mechanically locking saidpair of blades to said printed circuit board, said locking tab meansbeing formed with one end of gradually reducing width to facilitateinsertion of the locking tab means in said tab receiving recessportions.

References (Iited in the file of this patent UNITED STATES PATENTS2,790,961 Del Camp Apr. 30, 1957 2,922,138 Comins Jan. 19, 1960 FOREIGNPATENTS 924,279 Germany Feb. 28, 1955

